Question: Which is the agglutinative language for the official language of Achaemenid Empire?
Paraphrase: What is the agglutinative language for the Achaemenid Empire's official language?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q389688 wdt:P37 ?obj . ?obj wdt:P31 wd:Q171263 } 
Answer: Elamite, Sumerian